Thread control device for sewing machines



Aug. 22, 1961 R. HUGHES ,9 0

THREAD CONTROL DEVICE FOR SEWING MACHINES Filed March 2, 1959 2 Sheets-Sheet l FIELZ.

INVENTOR; ROBERT HUGHES Y W4 /7wdan ATTYS Aug. 22, 1961 R. HUGHES THREAD CONTROL DEVICE FOR SEWING MACHINES Filed March 2, 1959 2 Sheets-Sheet 2 ATTYS.

United States Patent 2,997,010 THREAD CONTROL DEVICE FOR. SEWING MACHINES.

Robert Hughes, 206 Sylvania Ave., Folsom, Pa., assignor of forty-five percent to Samuel E. Elkins, Nazareth, Pa., and ten percent to J. Lawrence Davis, Bangor, Pa.

Filed Mar. 2', 1959, Ser. No. 796,675. 4 Claims. (Cl. 112254) The present invention relates broadly to sewing machines and more. specifically to mechanism for automatically and continuously tensioning threads used in sewing machines, whether of a domestic or commercial type.

Heretofore, tensioning devicesv on sewing machines have been inthe nature of complicated devices such as take.- ups and/or frictional devices. Such tensioning devices have not been entirelysatisfactory and were not susceptible of. automatically compensating for variances in threads used such as tensile strength which varies with different dyes and colors. In other types of known tension control devices there is an actual drag on the thread resulting in a tug of war between the feed mechanism and the tensioning device. Other known devices required a manual tension adjustment for each and every tensile strength thread.

It is an object of the present invention to. provide, a thread tension control device for sewing machines which eliminates failures and drawbacks in previously known devices and which device. is applicable. to. different types of sewing machines.

Another object of the, present invention is to provide a thread tension control device utilizing a freely pivotally mounted pendulum having a grooved thread roller around which thread from the spool passes before passing to the thread feed and needle in a known manner.

An additional object of the present invention is to provide. a thread tension control device for sewing machanes which will give automatic compensationv for different tensile strength materials without the necessity of manual tension adjustments. and which device permits the speed of sewing machines. to be greatly increased ascompared with limitations set. up in operation with other types of devices due to the type of tension used.

Another object ofv the present invention is. to provide a thread tension control device for sewing machines in the nature of a simple, free swinging pendulum wherein the. location of the pivot efiects. actual controlling of amount of. tension dependent upon the amount. of weight in the pendulum below its pivot.

Other and additional objects and advantages of the present invention will be more readily apparent from the following detailed description of an embodiment thereof when taken together with the accompanying drawings, in which: 7

FIG. 1 is a front elevational view of a standard type of sewing machine with the thread tension control device operatively associated therewith;

FIG. 2 is a fragmentary enlarged view of a portion of the sewing machine of FIG. 1 showing details of the present invention;

FIG. 3 is a fragmentary sectional view taken on line 3-3 of FIG. 2;

FIG. 4 is an end elevational view of the sewing machine and thread tension control device;

FIG. 5 is a fragmentary sectional view taken on line 55 of FIG. 2;

FIG. 6 is an enlarged fragmentary sectional view of alternative pendulum mounting means.

In the following description like reference characters will be applied to like members in the various views of the drawings and the present specification is tobe read and understood in this light.

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The normal features of construction and operation of standard types of sewing machines are well-known and a complete detailed discussion thereof is not considered necessary for the purposes of the present application. Only such parts as will furnish a basis for a description of the present invention will be set forth herein. The sewing machine generally designated 10 includes the usual bed plate 12 and arm 14. A head 16 is provided on the. free end of arm 14. A balance wheel 18 suitably driven by belt 20 or the like is operatively mounted in a usual manner.

Thread 22 is lead from a freely rotatably mounted spool 24 in a manner hereinafter to be described to a needle 26 on needle bar 28 which operate in the usual manner. A usual type of presser bar is generally indicated at 30. The thread 22 is as usual operatively associated with take-up means 32 and guide means 34 and 3.4a.

In many known types of domestic sewing machines, a friction type of thread tensioner was mounted on the front face of the machine such as by means of a boss 36 in which a bolt 38. was adjustably connected in screw threaded engagement and which bolt had thereon a fric; tion sheave adapted for increasing or decreasing tension of thread passing therearound depending upon adjust.- ment of the bolt 33. This boss and bolt 36, 38. combination will, as will appear hereinafter, be utilized, in one embodiment of the invention for mounting of the present thread tensioning device.

The thread tensioning device of the present invention includes a plate member 40 having an opening there.-. through and through which bolt 38 is adapted to pass for engaging in boss. 36 in screw threaded engagement therewith and constitutes the sole mounting for the plate on the sewing machine. A thread guide member 42. is mounted on the plate in the direction of lead in of thread from spool 24 by means of a screw or bolt 44 and consists in facing dished discs 46 and 48 rotatably mounted on bolt 4-4, the tension of which can be adjusted by spring 50. This guide member is for the purpose. of keeping the thread smooth regardless of thread twist but does not serve in any way to tension the thread as in other types of take-ups common in sewing machines. A first grooved thread guide wheel 52 is freely rotatably mounted on plate 40 in spaced relation from thread. guide 42 by suitable means including a bolt 54 and a bearing generally designated 56 of any desired construction which will permit free and easy rotation of the guide wheel 52.. A simple pendulum 58 is freely movably journalled or mounted on plate 40 by means hereinafter to be described and shown in detail in. FIGS. 3 and 7 of the drawings. The lower end of pendulum 58 constitutes the weighted portion thereof, and the pendulum carries at its upper end as. an integral part thereof a mounting arm 66. for a sec.- ond thread guide. wheel 62 of the same construction g erally as that of'the wheel 52, details of one embodiment or type being shown in FIG. 5 of the drawings. It will be noted that the mounting arm 66' is substantially thinner than the lower weighted portion of the pendulum 58 to permit proper action of the pendulum arm. it will be noted that thread guide 42 and the first and second thread guide wheels 52 and 62 respectively are all in alignment to prevent undue tensioning of thread passing therearound.

As shown in FIG. 3 of the drawings, form of mounting means for the pendulum can consist of a nylon sleeve or bearing member 64 engaged in a bore 66 in the pendulum body and through which bolt 68 passes having its end in screw threaded engagement in a boss 70 for attachment of the pendulum. A washer 72 can be interposed between the head of bolt 68 and the pendulum body. The pendulum is free to swing by virtue of the nylon hearing as will be readily understood and with substantially no friction or tension thereon. It is accordingly a freely swinging simple pendulum.

In FIG. 6 there is shown a different type of support and bearing means for freely mounting the pendulum. In this embodiment a bore 66 again passes through the pendulum body and operatively inserted therein is a ball type bearing member generally designated 74 positioned by means of washers or the like 76 with the entire assembly being mounted by means of a bolt 68 coacting With threaded boss 70. The operation and construction of such bearings is well-known in the art and accordingly requires no detailed description herein.

The construction and mounting means for the second thread guide wheel 62 will be described with reference to FIG. of the drawings. The mounting arm portion 60 of the pendulum is fragmentarily shown having thereon a boss 64 in which a threaded bolt 78 is engaged. Bolt 78 has an outer portion on which an inner bearing race 80 is mounted in fixed relationship therewith by means of washers 82 and screw 84 of a type and character clearly indicated in FIG. 5. The guide wheel 62 has a central opening therethrough constituting an outer bearing race between which and the inner race 80, ball bearings 86 are interposed. This construction freely and rotatably mounts guide wheel 62 and in this connection the washers 82 are operatively engaged with circular slots 88 in opposed faces of guide wheel 62 for proper positioning and action thereof.

An adjustable thread guide 90 is mounted on plate 40 by coaction between slot 92 and bolt 94. A thread eyelet guide 96 is carried on the thread guide 90 and adapted, in conjunction with the adjustability feature of the guide 90, to align thread passing therethrough with the machine for proper operation.

In operation the thread 22 is passed around the underside of thread guide 42 thence over the top of first thread guide wheel 52 between that and the second thread guide wheel 62, passing under and around guide wheel 62 thence through guide eye 96, guide 34, thread take-up means 32 and guide 340, to the needle. When the thread is placed in tension in a known manner during sewing, this arran ement causes a displacing force on the pendulum through the second thread guide wheel 62. When this occurs the pendulum 58 will move from the position shown in full lines in FIG. 2 to that shown in dotted lines, the two positions being indicated 98a and 98b respectively. When this tension is relaxed the weight of the freely rotatably mounted pendulum will cause it to seek a normal vertical position and in so doing will compensate for the decrease in tension in the same manner that movement of the pendulum to the dotted line position would decrease tension upon movement. In actual operation the pendulum will move rapidly between these positions dependent upon the degree oftension on the thread and will in fact have a vibratory motion due to successive tension and no tension conditions. This movement automatically serves to compensate for the tension and no tension conditions and also serves to compensate for these conditions regardless of variances in the thread such as tensile strength.

The device of the present invention utilizes a simple, free and true pendulum action as distinguished from many known prior devices using either a counter-weight principle or a drag type of tensioning device requiring manual adjustment.

Manifestly minor changes in details of construction can be effected in the described device without departing from the spirit and scope of the invention as defined in, and limited solely by, the appended claims.

I claim:

1. In a sewing machine having a source of thread, intermittently operable stitching means and thread take-up means, mechanism for continually preparing and controlling thread condition and pull for presenting the exact amount of thread required for stitching to said stitching means, said mechanism comprising a fixed position thread guide wheel freely rotatably mounted on said machine, a free moving pivotally mounted pendulum on said machine having a portion thereof extending above its pivot point, a movable position thread guide wheel freely rotatably mounted on the upper end of the extended portion of said pendulum for movement therewith, the movable position wheel being positioned below said fixed position wheel and the thread take-up means, thread from said source sequentially passing over said fixed position thread guide wheel, between both said thread guide wheels and under and around said movable position thread guide to said thread take-up means, varying pulls on the thread under operating conditions of said sewing machine being automatically compensated and equalized by free pivotal movement of said pendulum whereby said exact amount of thread is presented to said stitching means.

2. In a thread control device for sewing machines as claimed in claim 1, an adjustable position thread eyelet guide mounted on said machine adapted to receive thread passing from said movable position thread guide and adapted to align thread passing therethrough with the take-up means of the machine.

3. In a thread control device for swing machines as claimed in claim 1, mounting means for said pendulum, said pendulum having a bore therethrough, a nylon bearing sleeve inserted in said bore and a bolt passing through said nylon bearing and secured to said machine.

4. In a thread control device for sewing machines as claimed in claim 1, mounting means for said pendulum, said pendulum having a bore therethrough, a ball bearing member inserted in said bore, and a bolt passing through said bearing member securing it to said machine.

References Cited in the file of this patent UNITED STATES PATENTS 920,185 Nussbaumer May 4, 1909 

